Great discussion. Thank you Ste for the model and the schematic! Saved me tons of time.
I used a frequency measurement trick from @holger along with the tune functionality pointed out here (Basic Potentiometer simulation - #4 by holger) by @paulvdh to create a practical schematic for the tuning of a PWM circuit.
The goal is to use the 555 timer along with low-cost components that are lying around to create a PWM circuit for controlling a PC fan. A low audible noise is provided by ensuring a frequency slightly above the audible range (25kHz).
I am very grateful to the open-source community and to this forum for allowing me to do this in close to an hour. It really motivated me to learn more about KiCad and its simulation abilities.
Unfortunately as a new user I cannot share my schematic file for those attempting to do the same!